I would recommend that you post it first as a work progress in the forum. Keep us updated with the interesting progessions as you go. Perhaps even posting mini ptreview games of the game on the arcade. Since you now have power to update your game as it grows this was not available prior.

If you go this route you will have an audience already waiting for the full launch.

This will also give you feedback as you are in progress. Nothing worse for you in this process than spend months on something you thought to be great. Only to discover players did not.

Just my thoughts here . I also feel the arcade is improving and it would be good to work with it and give feedback to Scirra. So they can know how we feel about it and what would be better for us to showcase our games.